How Can I Test OSX Issues
Explanation of Internet Addressing
When using the Internet, you are assigned a Public IP address, such as 53.244.204.20 for IPv4 or 2000:3fab:84a6:c75b:82:d3c4:9fd3:6a38 for IPv6. You can verify your address at https://test-ipv6.com/. Communicating these addresses, as well as MAC addresses like cf:71:09:48:9f:cf, can be complicated and error-prone, especially for those who are not technically savvy. Furthermore, historical data about previous issues may not be readily available.
Navigating the World Wide Web
To access a website, such as https://jacobs.com, your computer first contacts a DNS server to translate the URL’s host portion (jacobs) and its Top Level Domain (com) into an IP address, like 186.52.124.197. Additionally, your computer and browser reveal their type when making web requests, for example, Mozilla/5.0 (Windows; U; Win 9x 4.90; SG; rv:1.9.2.4) Gecko/20101104 Netscape/9.1.0285.
Understanding the Significance of Default Gateways
The default gateway is typically automatically configured through DHCP and is represented by an address such as 172.30.96.25, with common endings of .1 or .254. Your computer sends all outgoing traffic to the default gateway for further routing. To troubleshoot IPv6 connectivity on Mac or Linux, you can refer to our in-depth guide at how-to-fix-ipv6-connectivity/.
IPv4 Routes and the Host IPv4 Route Table (inc. VPN)
netstat -rn -f inet | egrep -i "default|0/1|128.0/1"
0/1 172.18.12.193 UGScg utun3 default 172.30.96.25 UGScg en0 128.0/1 172.18.12.193 UGSc utun3
Note: We are not just looking for the default but also for any VPN that overrides the public v4 address space.
IPv6 Routes and the Host IPv6 Route Table (inc. VPN)
netstat -rn -f inet6 | egrep -i "default|2000::/3"
If you have IPv6 active the above should return at least one route (as per below) via a known interface such as “en0 " on a Mac.
default fe80:7833:7d80:4bd0:e3e7%en0 UGcg en0 default fe80::%utun0 UGcIg utun0 default fe80::%utun1 UGcIg utun1 default fe80::%utun2 UGcIg utun2 2000::/3 utun3 USc utun3
Note: We are not just looking for the default but also for any VPN that overrides the public v6 address space.
Debugging DHCP for both IPv4 and IPv6
To get a look at the low level DHCP configuration (Mac/Linux):
ipconfig getpacket en0
...
domain_name_server (ip_mult): {72.207.76.151, 244.71.69.84}
end (none):
...
So, in the above we are not getting IPv6 DNS servers from the DHCPv4 reply but…
ipconfig getv6packet en0
DHCPv6 REPLY (7) Transaction ID 0x80940b Length 76
Options[4] = {
CLIENTID (1) Length 14: DUID LLT HW 1 Time 668691856 Addr cf:71:09:48:9f:cf
DNS_SERVERS (23) Length 32: 2606:4700:4700::1111, 2001:4860:4860::8844
DOMAIN_LIST (24) Length 0: Invalid
SERVERID (2) Length 10: DUID LL HW 1 Addr 52:1d:a9:e6:1a:0e
}
Solving Connectivity Issues with Wired or Wireless Networks
When it comes to transmitting data to your router, you may be utilizing a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Tips for Apple macOS / OSX
No matter which version of OSX/macOS you’re using, whether it’s 10.14.5, 11.4.2, or 12.1.7, there are various tools available for fixing connectivity issues. However, these manual actions and scripts don’t provide a set of correlated values over time. This is where automated remote troubleshooting becomes invaluable, especially for teams that are embracing remote work and Work From Anywhere (WFA).
Useful Built-in Scripts for Troubleshooting
An extremely helpful tool on OSX/macOS is sudo wdutil info, which provides a dump of the current wireless settings to the CLI and can also be configured to generate specific logs for troubleshooting. For a more comprehensive option, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is only relevant to wireless at that specific point in time, similar to wdutil.
To run it in the background and have it write logs to /var/tmp/<blah>.tar.gz, use sudo nohup /usr/bin/sysdiagnose -u &. If you prefer to run it interactively (although there isn’t much interaction), you can execute sudo /usr/bin/sysdiagnose and it will display a privacy warning. When not run in the background, it should open Finder in the correct location, or you can navigate to /var/tmp using Finder with Cmd+Shift+G. Keep in mind that the file sizes are approximately 300MB or more.
Possibly Helpful Videos
P.S. Tips For Remote Network and Client Support
Digital work requires reliable connectivity. Whether for low latency or regular data streams, Wi-Fi, DNS, and network issues cause teams to lose time and productivity. Even worse is when support teams waste time trying to recreate and isolate issues! See how PanSift saves time, money, and frustration on all sides with instant remote troubleshooting 🏠🏝🛰.
